Prior research has shown that breastfed children have higher IQs. Now a new …

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Articles that involve breastfeeding are a lot like buses, it seems. There are none for ages, and then all of a sudden you get three at once. Yesterday, Matt reported on a pair of mammary-related studies, and today it's my turn with a paper in the current PNAS that identifies a gene involved with intelligence.

Defining the roots of intelligence is both tricky and ethically fraught. Tricky, because the way our brains turn out is a result of a complex interaction of genetics and environmental effects. Ethically fraught, because research which found that being smart was predetermined by DNA might have strong implications for concepts like equality and democracy.

It has been known for some time that children that were breastfed have higher IQs than those who received cows' milk or formula. It is thought that this effect is due to the presence of long-chain polyunsaturated fatty acids (LC-PUFAs) in breast milk. LC-PUFAs are used as building blocks for a host of different hormones and other signaling molecules in the body, such as prostanoids, leukotrienes and the like.

The study involved looking at the role of a gene involved in fatty acid metabolism, FADS2, on breastfeeding and IQ. Using two different birth cohorts, one in the UK and one in New Zealand, the researchers discovered a relationship between a genetic polymorphism of FADS2 and breastfeeding's effect on IQ. One specific SNP, rs174575, was identified as important. Although there was no difference in IQ linked tp the presence of the polymorphism alone, breastfed children carrying the polymorphism had a significant increase in IQ compared to carriers who were not breastfed. This difference was present in both the British and New Zealand cohorts. For children that were homozygous non-carriers, there was no effect of breastfeeding on IQ.

I find the study an interesting one. FADS2 is clearly not the gene for intelligence, not that such a single gene exists. However, it does seem to play an interesting role in modulating environmental determinants of intelligence. It also adds more weight to the idea that breastfeeding is the way to go. On top of the other benefits, unless you know your child is a homozygous non-carrier, you don't want to make them stupid, do you?